Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 mu m

作者：Birkby J L^*; de Kok R J; Brogi M; de Mooij E J W; Schwarz H; Albrecht S; Snellen I A G

来源：Monthly Notices of the Royal Astronomical Society, 2013, 436(1): L35-L39.

DOI：10.1093/mnrasl/slt107

• techniques: spectroscopic
• stars: individual: HD 189733
• planetary systems

We report a 4.8 sigma detection of water absorption features in the day side spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R similar to 100 000) spectra taken at 3.2 mu m with CRIRES on the VLT to trace the radial-velocity shift of the water features in the planet%26apos;s day side atmosphere during 5 h of its 2.2 d orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (V-sys = -3(-6)(+5) km s(-1)) and planet orbital velocity (K-p = 154(-10)(+14) km s(-1)), and determine a H2O line contrast ratio of (1.3 +/- 0.2) x 10(-3) with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection to 5.1 sigma with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectroscopy is suited to finding not just simple molecules like CO, but also to more complex molecules like H2O even in highly telluric contaminated regions of the Earth%26apos;s transmission spectrum. It is a powerful tool that can be used for conducting an immediate census of the carbon-and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.

• 出版日期2013-11